1. Field of the Invention
The present invention relates to a paging method and an apparatus thereof in a broadband wireless communication system. More particularly, the present invention relates to a paging method and an apparatus thereof of User Equipment (UE) located within a service area of a femto cell.
2. Description of the Related Art
In a cellular wireless communication system, a channel may deteriorate due to one or more of a geographical factor inside a cell, a distance between User Equipment (UE) and a base station, and movement of the UE, so that communication between the UE and the base station is hampered. More particularly, when a UE is located inside a closed building such as an office or a household, a channel between a base station and the UE may deteriorate in a region referred to as a shadow region. The UE located in the shadow region has difficulty in communicating with the base station.
A femto cell concept is proposed in order to provide a data service of a far higher level to even more users while addressing a service limitation of the indoor shadow region. The femto cell is a small cell service area formed by a femto base station (femto eNB or home dNB) which accesses a mobile communication core network via a broadband network installed in the indoor space. Since the femto cell has a very small cell service area compared to a macro cell, a plurality of femto cells may be installed inside one macro cell service area.
A macro base station may experience interference from a plurality of femto cells existing inside a cell service area of the macro base station. Therefore, to reduce an amount of interference by a femto base station to a macro base station, there is a conventional technique for turning off transmitter power of a femto base station that is not currently providing service to a UE.
Further, there is a conventional technique for allowing a UE to camp on a macro base station instead of a relevant femto base station, to increase efficiency when the UE exists inside the service area of the femto base station in the case where the technique for turning off transmitter power of the femto base station is used. That is, there is a technique for allowing an idle UE to receive a paging message from the macro base station by allowing the UE located inside the service area of the femto base station to camp on the macro base station.
However, when the UE located inside the service area of the femto base station camps on the macro base station, when an incoming call for the UE occurs, the UE that has been transmitting/receiving data via the macro base station performs an active handover to the femto base station, that is, performs a hand-in to transmit/receive data occasionally.
FIG. 1 is a view illustrating a paging technique of a UE located in a femto cell in a conventional broadband wireless communication.
Referring to FIG. 1, in step 110, a UE 100 located in the service area of a femto base station (femto eNB) 102 camps on a macro base station (macro eNB) 104. When an incoming call for the UE 100 occurs, a Mobility Management Entity (MME) 106 transmits a paging message to the macro base station 104 in step 112. In step 114, the macro base station 104 performs paging for the UE 100. In step 116, the UE 100 transmits a response message to the paging for the macro base station 104. In step 118, the macro base station that has received the response message transmits a registration message to the MME 106. In step 120, the MME 106 connects the incoming call to the macro base station 104.
In step 122, the macro base station 104 and the UE 100 sets up a connection and transmit/receive data. At this point, when detecting the femto base station 102, the UE 100 performs an active handover to the femto base station 102, i.e., a hand-in in step 124, and transmits/receives data via the femto base station 102 in step 126.
As described above, according to the conventional art, even when a UE is located in the service area of a femto base station, the UE camps on a macro base station and receives a paging message from the macro base station, so that the UE starts to transmit/receive data via the macro base station. However, frequently, since the UE is located in the service area of the femto base station, the UE may detect the femto base station while transmitting/receiving data, and perform an active hand-in to the detected femto base station. Here, the active hand-in is one of a plurality of handover techniques causing a burden to a system. Since the active hand-in occurs frequently, the load on the system increases.